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Commit a200ee18 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
Browse files

mm: set_page_dirty_balance() vs ->page_mkwrite() 



All the current page_mkwrite() implementations also set the page dirty. Which
results in the set_page_dirty_balance() call to _not_ call balance, because the
page is already found dirty.

This allows us to dirty a _lot_ of pages without ever hitting
balance_dirty_pages().  Not good (tm).

Force a balance call if ->page_mkwrite() was successful.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3eb215de

include/linux/writeback.h

+1 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ int sync_page_range(struct inode *inode, struct address_space *mapping, 
			loff_t pos, loff_t count);

int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,

			   loff_t pos, loff_t count);

void set_page_dirty_balance(struct page *page);

void set_page_dirty_balance(struct page *page, int page_mkwrite);

void writeback_set_ratelimit(void);



/* pdflush.c */

mm/memory.c

+7 −2
Original line number Diff line number Diff line
@@ -1639,6 +1639,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
	struct page *old_page, *new_page;

	pte_t entry;

	int reuse = 0, ret = 0;

	int page_mkwrite = 0;

	struct page *dirty_page = NULL;



	old_page = vm_normal_page(vma, address, orig_pte);
@@ -1687,6 +1688,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 
			page_cache_release(old_page);

			if (!pte_same(*page_table, orig_pte))

				goto unlock;



			page_mkwrite = 1;

		}

		dirty_page = old_page;

		get_page(dirty_page);
@@ -1774,7 +1777,7 @@ unlock: 
		 * do_no_page is protected similarly.

		 */

		wait_on_page_locked(dirty_page);

		set_page_dirty_balance(dirty_page);

		set_page_dirty_balance(dirty_page, page_mkwrite);

		put_page(dirty_page);

	}

	return ret;
@@ -2322,6 +2325,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	struct page *dirty_page = NULL;

	struct vm_fault vmf;

	int ret;

	int page_mkwrite = 0;



	vmf.virtual_address = (void __user *)(address & PAGE_MASK);

	vmf.pgoff = pgoff;
@@ -2398,6 +2402,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
					anon = 1; /* no anon but release vmf.page */

					goto out;

				}

				page_mkwrite = 1;

			}

		}
@@ -2453,7 +2458,7 @@ out_unlocked: 
	if (anon)

		page_cache_release(vmf.page);

	else if (dirty_page) {

		set_page_dirty_balance(dirty_page);

		set_page_dirty_balance(dirty_page, page_mkwrite);

		put_page(dirty_page);

	}

mm/page-writeback.c

+2 −2
Original line number Diff line number Diff line
@@ -274,9 +274,9 @@ static void balance_dirty_pages(struct address_space *mapping) 
		pdflush_operation(background_writeout, 0);

}



void set_page_dirty_balance(struct page *page)

void set_page_dirty_balance(struct page *page, int page_mkwrite)

{

	if (set_page_dirty(page)) {

	if (set_page_dirty(page) || page_mkwrite) {

		struct address_space *mapping = page_mapping(page);



		if (mapping)